Metabolic disorders are diseases that involve changes in plasma metabolites of sick animals or humans. Almost 50% of dairy cows are affected by one or more metabolic diseases such as ketosis, fatty liver, laminitis, displaced abomasum, milk fever, downer cow syndrome, udder edema, metritis, retained placenta, infertility, or mastitis. The conventional view on metabolic disorders is that these diseases are related to the disturbance of one or more blood metabolites. These changes are generally interpreted as deficiencies or excesses of these nutrients in the diet, especially, around parturition.
High-grain diets (i.e. a diet rich in starch) may be implicated in the development of metabolic disorders. Feeding ruminant animals high-grain diets is a human-designed intervention to increase milk and meat production. However, ruminants do not naturally consume high-grain diets; rather, they eat mostly grass or forage diets. Since grain is rich in starch and poor in fiber content, feeding high-grain diets is associated with major changes in the gastrointestinal (GI) microflora, involving a switch from fiber-digesting bacteria to starch-digesting bacteria. Most of the starch-digesting bacteria are Gram-negative bacteria. These degrade starch to use it for their nutritional needs. During this process, large quantities of acids are released into the GI tract. As a result, the normally alkaline GI tract becomes more acidic. Furthermore, abundant starch increases the number of Gram-negative bacteria in the GI tract. This is associated with the release of great amounts (20-fold increase) of toxic compounds such as endotoxin or lipopolysaccharide (LPS). Endotoxin translocates into the host's blood circulation and causes a variety of alterations in blood metabolites, immunity, and health status.
Thus, metabolic disorders, particularly as a result of grain feeding in ruminant animals, are a significant problem and there remains a need for effective methods for preventing metabolic disorders, particularly in mammals such as dairy cattle.